Audio capturing devices such as video cameras or field recorders often record more than two channels of audio, sometimes four channels, sometimes eight or ten, etc. The inputs to these channels may vary widely depending on what the user has plugged into the device. For example, a HDV camera running in four channel mode may have microphones plugged into all four channels or may have microphones plugged into only three of the channels. Of the microphones that are plugged in, some may be mono microphones, each of which produces one channel of audio data unrelated to other channels, while others may be stereo microphones, each of which produces a pair of closely related stereo channels.
Different configurations of microphones and recording equipment produce audio files that need to be processed differently. For example, a 3-channel audio file produced by a configuration of a stereo microphone pair and one mono microphone must be processed differently than a 3-channel audio file produced by another configuration of three mono microphones. In this example, the two stereo channels of the first configuration need to be assigned to a pair of stereo speakers, while the mono channels of the second configuration need not be so assigned. Failure to map audio channels to the appropriate speakers or audio equipment would likely result in unintended, and possibly disturbing, auditory distortions or dissonance. Therefore, it is important for a media editing application processing an audio file to be cognizant of the configuration of microphones and recording equipment that produced the audio file.
Unfortunately, the configuration of microphones and recording equipment that produces an audio file is not always readily apparent to a media editing application processing the audio file. For example, an audio file that includes one mono channel and a pair of stereo channels usually does not include information on which two channels are stereo channels and which channel is the mono channel. A user of a media editing application intending to incorporate the audio from the audio file must, therefore, explicitly choose a configuration of audio channels. This is usually a manual process that is both tedious and prone to error.
What is needed is an apparatus or a method for automatically detecting the configuration of audio channels, a method that automatically eliminates silent channels and determines the relationships between remaining audio channels.